Running on MAC OSX. Had this problem on multiple machines at multiple studios I've worked at
Often every single mask will become corrupted.. usually after saving. They turn into what I attached below. Strangely these corruptions vanish when I zoom in leading me to believe it might be some display issue. Incredibly frustrating as I need to "fix" these by getting the selection from the "corrupted" mask and putting it on a new adjustment layer. Then replacing the corrupted mask with the new one to reset it.